Microwave amplifier

ABSTRACT

A double-tuned microwave amplifier comprising an outer conductive shell, a controlled charge carrier device disposed within said shell, and means operatively dividing the shell into two radial transmission mode, double-tuned cavities upon energization thereof by said device.

United States Patent 1191 Quirk 1 Oct. 15, 1974 MICROWAVE AMPLIFIER 3,238,469 3 1966 Stankcy 1111.; 330/56 3,323,072 5 I967 L' 330 56 [75] Inventor: Owensboro, 3,605,034 9/1971 R1121 et al. 330/56 y- I 3,718,869 2/1973 Gerlach 331/96 Assignee: General Electric p y, 3,803,514 4/1974 Camp, .11. 331/96 Owensboro, Ky. Primary Examiner-Stanley D. M1ller, Jr, [22] Flled: 1973 Attorney, Agent, 0r FirmN. J. Cornfeld; D. A. 2 APPL 406,201 Dearing; F. L. Neuhauser 521 US. Cl 330/56, 331/96, 333/83 [57] ABSTRACT 51 1111. C1. H031 3/60 A double-tuned microwave ampllfier compflsmg an [58] Field of Search 330/53, 56; Outer conductive She, a Controlled Charge Carrier 331 9 9g; 333 3 vice disposed within said shell, and means operatively dividing the shell into two radial transmission mode, [56] References Cited double-tuned cavities upon energization thereof by UNITED STATES PATENTS 3,048,802 8/l962 Jurcy 3'30/56 10 Claims, 4 Drawing Figures PAENIEB 021 1 51924 comm was GZMDSE Q06 MICROWAVE AMPLIFIER BACKGROUND OFTHE INVENTION 1 This invention relates to the art including microwave amplifiers, and more specifically, "to' such'amplifie'rs having double-tuned radial cavity characteristics.

A well known type of'microwave circuit-iscOmprised of a triode tube designed for operation at microwave frequencies and an associatedcircuitry in-the form of distributed constant transmission line sections. One common-formwhich has been utilized to amplify and- /or generate energy in the microwave energy band comprised so-called coaxial,transrnission, lineysecg tions. More recently, in order toiprovideamplification. and/or generation ,ofmicrowave energy with substan tially reduced overall size and with moreieompaet qonrg figuration, it has been proposed to utilize. radial modes of propagation in place of theearli'erdeveloped coaxial modes. An example of .such device for generation of microwave energy but not amplification thereof is found in US. Pat. No. 3,718,869 to H. W. A. Ger lach and assigned to the United States of America as represented by the Secretary of the Army. While the device disclosed and claimed therein may be operative to effect a foreshortening of its overall dimensions, this device, because it discloses only a single-tuned cavity oscillator, is devoid of any suggestion of the double-tuned radial cavity amplifier of this invention.

SUMMARY OF THE INVENTION It is, accordingly, a principal object of this invention, to provide a microwave amplifier characterized by a' exemplary, the shape being related for. convenience shown to be circular; however, it will be understood that rother configurationssueh as elliptic, rectangularor. otherv configuration well known in the art may be used with i-nthe scopeef this' i-nvention.

he view shown'in F l is substantially taken alongline 'l 'lof FIG. 2. some elements, which, strictly" speaking, would not be visible when viewed along line I-I ,'"have been added to the viewixof -F lG.;1 to show theirrelationship therein. 1

'Th'e'shell' 13 isformed with a main body portion 16 and is provided with a closure cap 41 having a centrally provided recess 43 and having a central aperture through-Whichthe-RF output COUPllIIgAS-IS :passed for purposes:explainedThereinbelow,iTheclosureEeap-is se-v cured to th'emainibodyl portion ofshellu13-by securing means- 24, '28; 42, 46, and 52iriserted=through closure cap apertures 26, 30, 44, 48,- and 54, respectively, and through aligned openings in a conductive plate 39 and ultimately fixedlyseeured in the. main body portion 16.

The controlled charge carrier device 11, asshown in FIG. 1, may be a triode, which may be of any conventional variety of high frequency planar electrode ceramic-metal construction. As is well known,.such a triode is provided with cathode, grid and plate electrodes (not shown) with a cathode terminal 15, grid terminal 17, and anode terminal or stud l9, respectively, conductively connected to the associated elec- .trodef The electrodes, as is well known, are separated "byceramic insulators 21, 23, and 25. The cathode is indirectly heated by current supplied from a source of In accordance with the invention, a double-tuned mi crow ave amplifier is provided having means defining a first radial mode resonant cavitybetween two terminals of a controlled charge carrier'device and a second radial mode resonant cavitydefined by one of said terminal and an inner wall amplifier.

These and other object'sof thisinventionwill bebe tter understood from the following description taken in connection with the accompanying drawings.-

BRIEF DESCRIPTION DRAWING FIG. I is an axial section of one embodiment of the invention with parts broken away for clarity.

FIG. 2 is a cross section of the device of FIG. 1 taken along the line II-Il of FIG. 1.

FIG. 3 is a graph of the power gain of thedoubletuned amplifier of the embodiment of FIG. 1.

FIG. 4 is an axial section of another embodiment of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS of a conductive enclosure' for said heater current (not shown) connected in any conventional manner to pins 27 through heater wires 29.

I DC bias on the anode of the triode is provided, in any conventionalmanner, from a DC source (not shown) such as through, in order, lead wire 3], conventional quarter wavelength choke 33, lumped constant'chok'e 35, andQlastly, a conductive disc 36 which is conductively connected-to the anode stud 19. The choke 33 is preferably formed as a distributed constant choke which in this instance would be a quarter wavelength thezdesired operating frequency of the device to miniimzq'leaiage of-"RF-energy through the line to the sourceof'DG The conductive disc 36 is provided with 'afce'nt ral aperture through which the anode stud l9 'passe'sinatigh t'fin'the disc 36 being spaced from the plate 39 by meansof an insulating disc 40. The disc 40 "may be. constructed of beryllia or other heat conductive materialland thus provides a heat conductive path to the shell 13. The use of the disc 40 is optional and may be omitted if not required.

' Inasmuch as the shell 13 of the device is normally maintained at ground potential, the cathode terminal 15 of the device is supported by means of a distributed constant quarter wavelength cathode choke 37 formed by a cathode line 55 and an inner coaxial wall 54, thereby isolating the cathode terminal from ground potential in the manner well known to those skilled in the I art. Direct current connection tothe cathode of the triinsulate it from the-cathode line 55 which-is electrically connected to shell 13.

The conductive plate member 39, which as disclosed above is fixedly secured to the shell 13, is also conductively connected to the grid terminal I7."Aperture's '34, 32 are provided in' said 7 plate to permit the passagetherethrough of the connection 31 from the quarter wave anode choke 33and-the ceramic anode insulator 25, respectively.

The RF output coupling 45 may be of any conventional type such as that used in the coaxial designs. The inner terminal .47 thereof may be provided with a disclike probe 49 which, as shown, is positioned in space relation to the anode stud l9 of'the tube.

RF input is supplied through a conventional terminal 51 having a probe 53 located in the cathode cavity '14 formed by the cathode line 55 in capacitiverelation that achieved-with prior art amplifiers.

Referring to FIG. 4, a second embodiment constructed in accordance with theinvention herein is shown wherein transistor 66 ,is used as thecontrolled charge carrier device. The transistor 66 is supported with a shell 60to provide a doubletunedresponsesimilar .;to .thatachieved with the embodiment-shown in with the interior wall of the main body portion 16 of shell 13. I

In operation, and assuming that the tube has been supplied with the conventional DC potential, heater current, and an RF input, a first anode cavity 57 operating in a radial transmission mode is formed in accordance with the invention between the plate 39and the surface of disc 36 that is in juxtaposition with the adjacent surface of the anode ceramic 25.A second radial mode anode cavity 59 is formed between the remote or free surface of thedisc 36 and the inner wallof the recess 43.

Coupling between the first-and second anode cavities 57, 59 is achieved througha transfer of electromagnetic wave energy from the conductive enclosure for first anode cavity 57 represented by conductive plate 39, the innerwall of the recess 43 and the surface of disc 36 adjacentthe anode ceramic 25 to the conductive enclosure for the second anode cavity 59 represented by theinner wall of closure cap 41 and the surface of conductive plate 36 opposite anode ceramic 25 in accordance with principles well known in the art.

An input tuning screw 52 mounted in shell 13 isprovided in cathode cavity 14. Adjustment of the tuning screw 52 adjusts the electrical characteristics of the cathode cavity in'a wellknown manner. Similarly, an output tuning screw 56, mountedin closure cap 41, is provided in' thesccond anode cavity 59 for adjustment of the electrical characteristics thereof. Also; the insulator 40 provides dielectric loadingofthe resonant cavity 57. However. it may be omitted and the loading effect thereof be replaced by other conventional tuning means. 1 To illustrate the response characteristicsofa doubletuned radial cavity amplifier constructed'in'data taken from this amplifier, with='this invention, anamplifier was made substantially as shown in FIGS.1 and 2 using a conventional high-frequency-triode tube type as the controlled charge carrier-device. The amplifier soconstructed was operated with a DC voltage source in the anode circuit of 700 volts with a power output of 150 watts. FIG. 3 shows a graphical representation of data taken from this amplifier, the ordinate being calibrated for the change in power gain from a reference level of I08 db. (corresponding to the "0-ordinate value) and the abscissa being calibrated to indicate frequenciesin megahertz between 5,000 and5,250. As can be seen, the graphical representation of this data shows the characteristic form of a conventional double-tunedamplifier. It is significant to note that as shown in FIG. 3

FIGS. 1; and.-3.'The transistor 66, which may be of .a conventional three-terminal construction, has a collector, base, and emitter (not shown) with collector, base, and emitter terminals 71, 76, and 77, respectively, attached thereto. The transistor maybe of any conventional construction and further may be eitheraP-N-P or N-P-N type.

The shell 60 is provided with end walls 6 l'and 62 and a mainbody portion 109. The RF output coupling 63 and input coupling are supported in end walls 6] and62, respectively. A conductive. plate 73 is coupled between the base terminal 76 and the walls of the main body portion 109 of shell 60 anddivides the shell 60 into two conductive chambers. A heat conductive insulator 93, is positioned around collector terminal 71 to insulate plate 73 from a conductive plate 69 which is DC-connected to the endof collector terminal 7]. The insulator also aids in supporting the disc 69. Similarly, a heat conductive insulator is positioned around emitter terminal 77 to insulate conductive plate 73 from a conductive plate l07,'which is DC connected to the emitter terminal 77. The'insulators'lOS, 107 function in a similar manner to the insulator 40 (FIG. 1) and, likewise, may be omitted if desired. I

i The RF output coupling 63 may be in accordance with that shownin FIG. 1; The disc-like probe '64 of coupling 63 is' spaced from the collector 71' and the conductive plate 69 t'o provide RFcoupling ftherebetween in' 'acc ordanc e with well known principles.

Similarly, the RF input coupling 95 in endwall 62 has a disc-like probe 97 spaced from emitterterminal 77 and conductive plate 'l07 to provide an RF input to the transistor 66. The RF input is preferably transmitted as shown in FIG. 4 through double-tuned radial transmission'mode' cavities 96, 99. Thefir st input cavity 96 is formed'by the inner surface of'end'wall 62 and the surfaceo'f'plate 1'07 remote'from spacer 105. The second emitter cavity 99 is formed by the surface of plate 107 interfaced with spacer 105 and the surface of plate 73. Coupling between cavities 96, 99 is in accordance with the principles discussed in regard to'the cavities 57', 59 of the embodiment of FIG: 1' except that the energy is coupled from the'outermost cavity 96 tothe-innermost cavity 99 rather than'fromthe innermost cavity 57 to the outermost cavity 59.

It will be apparentto those skilled in the art that a single-tuned resonant emittercavity may be" substituted for the double-tuned emitter cavity shown in FIG. 4.

conventional manner, such a current path through, in

order, lead wire 87, passing through a feed-through capacitor 85 in the shell 60, a conventional lumped constant choke 78 and conductive plate 107 which is electrically connected to emitter terminal 77.

DC bias to the collector may be provided in any conventional manner such as along the circuit path through, in order, lead wire 83, passing through a feedthrough capacitor 81 in shell 60; a conventional lump constant choke 67 and the conductive plate 69 which is electrically connected to collector terminal 71.

The operation of the embodiment of FIG. 4 is essentially the same as that of the embodiment of FIGS. 1 and 2. With proper DC biases placed on the emitter and collector terminals 77, 71 and with an RF input supplied to terminal 95, a first collector cavity 101 operating in the radial transmission mode is formed by the plate 73, and the surface of plate 69 juxtaposed the adjacent surface of the insulator 93. A second radial mode anode cavity 103 is formed by inner surface of end wall 61, the surface of plate 69 opposite the insulator 93.

Coupling between the radial cavities 101, 103 is in accordance with that discussed in regard to the embodiment of FIGS. 1 and 2.

Tuning screws 65 and 79 are provided in end walls 61, 62, respectively, and enable fine tuning of the cathode cavity 96 and second radial cavity 103, respectively, according to principles well known in the art.

it will be apparent to those skilled in the art that an amplifier constructed in accordance with the invention herein may be operated with the anode cavities either double-tuned" (i.e., tuned to the same frequency) or stagger-tuned" (i.e., tuned, respectively, to complementary frequencies on each side of a center frequency) in accordance with well known principles such as set forth in Electronic and Radio Engineering, McGraw-Hill Electrical and Electronic Engineering Series, Chapter 12, pp. 400-442 (4th Ed., 1955).

The invention thus described provides a new and improved microwave amplifier having a compact design and/more particularly, having a double-tuned radial transmission mode resonator yielding an improved power gain bandwidth product.

While the invention has been shown and described with respect to specific embodiments thereof, it is not intended to be limited to the particular forms shown and described. Accordingly, the appended claims are intended to cover all modifications within the spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is;

1. A microwave frequency amplifier comprising:

a. a conductive shell having a main body and at least one end wall, said main body having a longitudinal axis of symmetry intersecting said at least one end wall;

b. a controlled charge carrier device for operation at microwave frequencies supported within said shell, said device having first, second, and third terminals;

c. an RF input terminal supported in said shell electrically coupled to said first terminal;

d. means in said shell defining a first resonant cavity between the second and third terminals of said device radially of said axis and a second resonant cavity between said third terminal and said at least one end wall radially of said axis;

e. coupling means for transmitting electromagnetic energy from said first to said second cavity; and

f. a double-tuned radial resonant circuit being provided by the electromagnetic coupling of said cavities upon RF energy being supplied to the RF input, thereby energizing said device and said cavities to operate at microwave frequencies.

2. The amplifier of claim 1 wherein said cavity defining .means comprises a first conductive plate electrically connected to the second terminal of said devic and to the main body portion.

3. The amplifier of claim 2 wherein said cavity defining means further comprises a second conductive plate electrically coupled to the third terminal, said first cavity being formed between said first and second plates and said second cavity being formed between said at least one end wall and said second plate; and wherein an RF output coupling is mounted in said at least one end wall for coupling microwave energy out of said shell.

4. The amplifier of claim 1 further comprising a first input means in said shell defining a first input cavity radially of said axis forv transmitting electromagnetic energy from said RF input to said first terminal.

5. The amplifier of claim 1 further comprising a second input means defining a second input resonant cavity radially of said axis, said second input cavity being electromagnetically coupled between said first input cavity and said first terminal to transmit electromag netic energy therebetween.

6. Microwave frequency amplifier comprising:

a. a conductive enclosure;

b. a controlled charge carrier device having at least two terminals, said device being supported within said conductive enclosure;

c. means in said enclosure defining a first radial mode resonator circuit between two of said at least two terminals and a second radial mode resonator circuit between one of said two terminals and said en closure, said first and second resonator circuits being energized by operation of said controlled charge carrier device at microwave frequencies; and

(1. means coupling said first and second resonator circuits to provide a double-tuned resonator arrangement, thereby to provide increased gain-bandwidth V for said amplifier.

7. The amplifier of claim 6 wherein said circuit defining means comprises a first conductive plate electrically connected to the other of said two terminals of said device and to said enclosure.

8. The amplifier of claim 7 wherein said conductive enclosure comprises a main body portion and at least one end wall and wherein said circuit defining means further comprises a second conductive plate electrically coupled to said one terminal, said first cavity being formed between said first and second plates and said second cavity being formed between said second plate and said at least one end wall.

9. The amplifier of claim 6 wherein said device is a triode, said one terminal being an anode terminal, said other terminal being a grid terminal.

10. The amplifier of claim 6 wherein said device is a transistor, said one terminal being a collector terminal,

said other terminal being a base terminal. 

1. A microwave frequency amplifier comprising: a. a conductive shell having a main body and at least one end wall, said main body having a longitudinal axis of symmetry intersecting said at least one end wall; b. a controlled charge carrier device for operation at microwave frequencies supported within said shell, said device having first, second, and third terminals; c. an RF input terminal supported in said shell electrically coupled to said first terminal; d. means in said shell defining a first resonant cavity between the second and third terminals of said device radially of said axis and a second resonant cavity between said third terminal and said at least one end wall radially of said axis; e. coupling means for transmitting electromagnetic energy from said first to said second cavity; and f. a double-tuned radial resonant circuit being provided by the electromagnetic coupling of said cavities upon RF energy being supplied to the RF input, thereby energizing said device and said cavities to operate at microwave frequencies.
 2. The amplifier of claim 1 wherein said cavity defining means comprises a first conductive plate electrically connected to the second terminal of said device and to the main body portion.
 3. The amplifier of claim 2 wherein said cavity defining means further comprises a second conductive plate electrically coupled to the third terminal, said first cavity being formed between said first and second plates and said second cavity being formed between said at least one end wall and said second plate; and wherein an RF output coupling is mounted in said at least one end wall for coupling microwave energy out of said shell.
 4. The amplifier of claim 1 further comprising a first input means in said shell defining a first input cavity radially of said axis for transmitting electromagnetic energy from said RF input to said first terminal.
 5. The amplifier of claim 1 further comprising a second input means defining a second input resonant cavity radially of said axis, said second input cavity being electromagnetically coupled between said first input cavity and said first terminal to transmit electromagnetic energy therebetween.
 6. Microwave frequency amplifier comprising: a. a conductive enclosure; b. a controlled charge carrier device having at least two terminals, said device being supported within said conductive enclosure; c. means in said enclosure defining a first radial mode resonator circuit between two of said at least two terminals and a second radial mode resonator circuit between one of said two terminals and said enclosure, said first and second resonator circuits being energized by operation of said controlled charge carrier device at microwave frequencies; and d. means coupling said first and second resonator circuits to provide a double-tuned resonator arrangement, thereby to provide increased gain-bandwidth for said amplifier.
 7. The amplifier of claim 6 wherein said circuit defining means comprises a first conductive plate electrically connected to the other of said two terminals of said device and to said enclosure.
 8. The amplifier of claim 7 wherein said conductive enclosure comprises a main body portion and at least one end wall and wherein said circuit defining means further comprises a second conductive plate electrically coupled to said one terminal, said first cavity being formed between said first and second plates and said second cavity being formed between said second plate and said at least one end wall.
 9. The amplifier of claim 6 wherein said device is a triode, said one terminal being an anode terminal, said other terminal being a grid terminal.
 10. The amplifier of claim 6 wherein said device is a transistor, said one terminal being a collector terminal, said other terminal being a base terminal. 